Yes! It is a fermented product and unpasteurized. If you open it at room temperature it will sometimes fizz up out of the bottle. You have to keep it in the fridge or the natural enzyme action will die down. The manufacturer claims health benefits from this action. I just know it's the best soy sauce I have tried and it's the ONLY sauce I eat with sushi. Seriously, we always get sushi as take-out so we can eat it at home with our preferred soy sauce and real wasabi.